Copper-based alloys are widely used to make automobile radiator fin stock. The fabrication of radiators involving the use of molten solder baths and high temperature solders, and the service environment for radiators with modern high temperature automobile engines, both dictate that radiator alloys have good thermal conductivity and high softening temperatures.
Electrical applications for copper-based alloys also require that the alloys have high softening temperatures, to resist the high temperatures often generated in high voltage electrical switching applications. Of course for such electrical applications the alloys must also have good electrical conductivity.
A wide variety of different copper-based alloys have been proposed in the past for use in such automotive and electrical applications and the effects of various alloying elements on the alloys for such services have been carefully studied. Studies on softening temperatures, for instance, have been described in U.S. Pat. No. 3,649,254 to I. S. Servi, with particular emphasis in this patent on copper-tin-oxygen alloys. Frequently such alloys required the use of very costly alloying elements and/or elements with high toxicity. Servi, for instance, describes the use of silver as an alloying element to raise softening temperature. Another alloy in commercial use uses cadmium as the principal alloying element.
Alloys have been described which attempt to avoid the use of expensive and/or toxic alloying elements and still obtain properties of the type required for automotive and/or electrical applications, U.S. Pat. No. 3,773,503 to P. J. Kranz, et al, describes an alloy for automotive use in which the principal alloying elements are 20-150 ppm phosphorus and 200-400 ppm tellurium alloyed in copper. Similarly, U.S. Pat. No. 3,700,842 to E. A. Attia describes an electrical service alloy in which the principal alloying elements are 4,000-6,000 ppm tellurium and 70-120 ppm phosphorus in oxygen free high conductivity copper. These alloys, while providing the needed properties and avoiding the use of unduly or expensive toxic materials, often have the disadvantage that they require the use of high purity (and therefore expensive) copper. In addition, they utilize large amounts of the alloying elements (especially tellurium), also adding to the cost of the alloy.
U.S. Pat. No. 4,311,522 to R. Batra, et al, describes a copper-based alloy containing selenium and manganese as a replacement for copper-silver alloys. These alloys are described as significantly better in their properties than copper-tellurium, copper-sulfur-tellurium or copper-manganese-tellurium alloys.
In another context, the International Copper Research Association (INCRA) has sponsored a study of ternary copper alloy properties. Among the alloys studied was a copper/22 ppm selenium/60 ppm tin alloy. The study is reported in the "Contractor Report" for INCRA Project No. 344, "Solute Effects In Very Dilute Ternary Copper Alloys", by M. Ohring of Stevens Institute of Technology (January, 1983). There is also a paper by Pitt, et al, Met. Trans., 10A, 809 (1979) briefly describing property studies of copper/selenium/tin alloys with less than 100 ppm total selenium and tin content.
It would be advantageous to have a lower cost copper-based alloys which employ as alloying elements materials which are neither unduly expensive nor toxic and which need not be used in large concentrations. Such alloys would of course need to have the required properties for either automotive or electrical use. The alloys of this invention meet such requirements.